1. Field of Invention
The present invention relates to a base insert device for paper bags. The apparatus has folding devices, gluing stations that apply glue to the regions of the folds and/or to sheets provided for gluing to the base, and a pressing station in which the folded bases and the sheets are brought into contact and adhered to one another.
2. Description of the Prior Art
Devices of this type are used in the production of various types of bags. These bags include, for example, the so-called valve bags in which valve patches are usually inserted when manufacturing the bases of the bags. The bases are frequently designed as crossed bases as illustrated, for example in the patent applications DE 090 145 48 U1 and DE 3020043 A1. In order to provide the bases and the inserted valve patches with a lasting cohesion, parts of the bases are stuck one below the other and/or to the valve patches with the help of glue.
For this purpose, glue is applied to either the regions of the base folds to be glued or the sheets provided to them, thus all the regions that are to be glued to one another and these are subsequently glued to one another by merging them or folding them together.
A format-specific glue application usually takes place in the following manner: A format part attached on a rotating roller is brought into contact during the rotation of said roller with a glue roller or with other glue storing components or transfer components and is thus supplied with glue. In the further course of the rotation of the roller, the format plate transfers the glue stored on it onto each region of the subsequently formed bases of the bags or the sheets to be glued. For this purpose, the format part is provided with characteristic ridges that are adapted to a definite bag format. The format parts are replaced for producing bags having other formats on the base insert device. This type of glue application has stood the test of time since it enables the clean and format-specific application of large quantities of the starch glue, which is otherwise difficult to handle.
The words “format-specific glue application” refers toga form of application that is adapted to the type and the format of the bag. In this form of application, the glue is usually applied in a flat manner, whereby special significance is accorded to the edges of the form for the durability and the impermeability of the bags.
However, the disadvantage is that this method of glue transfer makes it necessary to provide and subsequently clean a plurality of glue transfer components, for instance the format rollers and the format parts.
Therefore the object of the present invention is to further improve the design of the base insert device in such a way that these glue transfer components can be totally omitted or at least reduced in number while still enabling a format-specific glue application.
The present invention is based on the well-known base insert devices, which exclusively comprise gluing stations that require format parts for defining the format of the glue application.